Cracking or popping your knuckles is the act of releasing gasses from the synovial joints in the fingers or what ever part you are popping. While it can cause some slight damage to the joints and stretching to ligaments, it certainly will not cause arthritis. The cause of which to date is not known.
However the fact that you have this habit does not mean that you may not be suffering from some form of arthritis anyway. The best way to get answers to this is to have a word with your doctor and have the situation professionally assessed as soon as possible as early treatment can avert a lot of damage to joints.
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